DEVELOPMENT OF SLURRY ROTARY DRYER

Abstract

Drying is ubiquitously used operation that improves storage life of agricultural produce, either solid, liquid or slurry. This study was aimed at development of a slurry rotary dryer that uses gas fuelled combustion as a source of energy to effectively remove moisture from slurry materials and capable of satisfying the cost factor and product quality with locust bean effluent and palm oil milled effluent as test samples. The dryer was constructed at Agricultural Engineering Workshop of Federal University of Technology, Akure. It consists of the following components; drying cylinder, stainless brush, burner, shaft, collector, feeder, plastic drum, plastic pipe, rubber hose, stand (base). The drying experiment was carried out at constant feed rate of 30 kg/hr, at drum speed of (5, 7 and 10 rpm), each drum speed was evaluated at temperature levels (90, 110 and 130 0C) using both palm oil mill and locust bean effluents. Proximate analysis was carried out on the dried samples using standard methods. Statistical analysis for proximate composition of the dried locust bean effluent at different temperatures and speeds showed significant effect of temperature on the percentage of the proximate content with the highest values observed at 90 0C for protein, moisture content, and fat at speed of 10rpm respectively. There was significant effect of temperature on the carbohydrate, ash and fibre with the highest observed at 130 0C with speed of 5rpm. For dried sample of palm oil mill effluent temperature has significant effect on the carbohydrate, protein, moisture content, fat, ash and fibre. A better performance was obtained at drying temperature of 90 0C and speed of 7rpm in terms of protein and carbohydrate compared to 110 and 130 0C. Speed has significant effect on the carbohydrate, protein, moisture content, fat, ash and fibre. It was observed that 5 rpm performed better compares to 7 rpm and 10 rpm for moisture content of the dried sample. The highest drying efficiency and output capacity obtained was 75% and 22.50kg/hr for dried sample of locust bean effluent while 70.8% and 21.32kg/hr for dried samples of palm oil mill effluent at 90 0C with speed of 10 rpm . These dried samples can serve as supplements in animal feeds. The dryer can be scaled up for industrial processing effluents of agricultural produce and used to dry different types of effluent. Keywords: Drying, Slurry rotary dryer, Design, Effluent